In vitro antibacterial properties and UV induced response from Staphylococcus epidermidis on Ag/Ti oxide thin films
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Implanted materials are susceptible to bacterial colonization and biofilm formation, which can result in severe infection and lost implant function. UV induced photocatalytic disinfection on TiO2 and release of Ag+ ions are two promising strategies to combat such events, and can be combined for improved efficiency. In the current study, a combinatorial physical vapor deposition technique was utilized to construct a gradient coating between Ag and Ti oxide, and the coating was evaluated for antibacterial properties in darkness and under UV light against Staphylococcus epidermidis. The findings revealed a potent antibacterial effect in darkness due to Ag+ release, with near full elimination (97 %) of viable bacteria and visible cell lysis on Ag dominated surfaces. The photocatalytic activity, however, was demonstrated poor due to low TiO2 crystallinity, and UV light irradiation of the coating did not contribute to the antibacterial effect. On the contrary, bacterial viability was in several instances higher after UV illumination, proposing a UV induced SOS response from the bacteria that limited the reduction rate during Ag+ exposure. Such secondary effects should thus be considered in the development of multifunctional coatings that rely on UV activation.
KeywordsTiO2 Photocatalytic Activity Oxide Thin Film Plasma Electrolytic Oxidation Bacterial Viability
This work was supported by the Swedish Foundation for Strategic Research (SSF), through the ProViking Project.
- 5.Maness P, Smolinski S, Blake D, Huang Z, Wolfrum E, Jacoby W. Bactericidal activity of photocatalytic TiO2 reaction: toward an understanding of its killing mechanism. Appl Environ Microbiol. 1999;65:4094–8.Google Scholar
- 28.United States Environmental Protection Agency. Ultraviolet disinfection guidance manual for the final long term 2 enhanced surface water treatment rule. http://www.epa.gov/ogwdw000/disinfection/lt2/pdfs/guide_lt2_uvguidance.pdf; 2006 Nov pp. 1–436.
- 36.Guillobel H, Leitão AC. Characterization of Staphylococcus epidermidis mutants sensitive to ultraviolet radiation. Mutat Res. 1988;193:1–10.Google Scholar
- 37.Sondi I, Salopek-Sondi B. Silver nanoparticles as antimicrobial agent: a case study on E. coli as a model for Gram-negative bacteria. J Colloid Interf Sci. 2004;275:177–82.Google Scholar